U.S. patent number 3,812,508 [Application Number 05/327,164] was granted by the patent office on 1974-05-21 for camera provided with a device for automatically photographing dates of photographing.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Mutsuhide Matsuda, Mitsutoshi Ogiso, Mutsunobu Yazaki.
United States Patent |
3,812,508 |
Matsuda , et al. |
May 21, 1974 |
CAMERA PROVIDED WITH A DEVICE FOR AUTOMATICALLY PHOTOGRAPHING DATES
OF PHOTOGRAPHING
Abstract
An adjustable device for photographing data, numbers or
characters indicating the date of photo-taking is provided in a
camera. An illumination lamp illuminates the selected numbers or
characters in association with the releasing of the shutter and the
illuminated numbers or characters are photographed on the film. The
duration of illumination of the lamp is controlled by a time
control device actuated in association with the releasing of the
shutter.
Inventors: |
Matsuda; Mutsuhide (Tokyo,
JA), Ogiso; Mitsutoshi (Kawasaki, JA),
Yazaki; Mutsunobu (Kanagawa-ken, JA) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JA)
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Family
ID: |
27278511 |
Appl.
No.: |
05/327,164 |
Filed: |
January 26, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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110814 |
Jan 29, 1971 |
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Foreign Application Priority Data
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Jan 29, 1970 [JA] |
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45-9496 |
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Current U.S.
Class: |
396/317 |
Current CPC
Class: |
G03B
17/245 (20130101); G03B 2217/243 (20130101) |
Current International
Class: |
G03B
17/24 (20060101); G03b 017/24 () |
Field of
Search: |
;95/1.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Horan; John M.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Parent Case Text
This is a continuation, of application Ser. No. 110,814, filed Jan
29, 1971 now abandoned.
Claims
1. A camera provided with a device for photographing the date of
photo-taking comprising:
data rings of transparent material carrying indicia thereon,
display rings connected to said data rings for operating them
exteriorly of said camera, said display rings carrying thereon
indicia identical with those on said data rings to enable an
operator to observe them exteriorly of said camera,
said camera having a lens tube and said data rings and said display
rings being rotatably mounted around said lens tube, said data
rings carrying indicia on the inner wall surfaces thereof,
a lamp for illuminating said indicia on said data rings,
an optical system for directing the images of said indicia on said
data rings illuminated by said lamp to a part of a focal plane of
an objective lens,
a slit provided between said data rings and said optical system for
directing a selected set of said indicia to said optical
system,
a shutter mechanism, and
a time control device actuated by releasing said shutter for
turning said
2. A camera as defined in claim 1, wherein said lamp is interposed
between said data rings and said display rings so as to illuminate
said indicia on
3. A camera as defined in claim 1, wherein said data rings have
their outer wall surfaces serving as reflective surfaces of a prism
for directing
4. A camera provided with a device for photographing the data of
photo-taking comprising:
data rings of transparent material carrying indicia thereon,
said camera having a film chamber and a light-proof frame, said
data rings being disposed between the film chamber and the
light-proof frame,
display rings connected to said data rings for operating them
exteriorly of said camera, said display rings carrying thereon
indicia identical with those on said data rings to enable an
operator to observe them exteriorly of said camera,
a lamp for illuminating said indicia on said data rings,
an optical system for directing the images of said indicia on said
data rings illuminated by said lamp to a part of a focal plane of
an objective lens,
a slit provided between said data rings and said optical system for
directing a selected set of said indicia to said optical
system,
a shutter mechanism, and
a time control device actuated by releasing said shutter for
turning said lamp on for a predetermined length of time, said time
control device being adjustable in accordance with the sensitivity
of a film used in said camera, and having a main switch for
preparing said camera for data photographing,
a data field display member capable of shifting from and into a
field of a finder of said camera, said data field display member
shifting in response to the closing and opening of said main
switch, thereby indicating whether
5. A camera as defined in claim 4, wherein said time control device
is adjustable in accordance with the sensitivity of a film used in
said
6. A camera as defined in claim 4, wherein said time control device
comprises a time constant circuit actuated by a start switch which
in turn
7. A camera as defined in claim 4, wherein said data rings have
their outer
8. A camera as defined in claim 4, wherein said lamp is disposed
within said data rings, and said data rings and said display rings
are in engagement with each other by means of gears provided along
the outer circumferences thereof, both of said rings having their
axes of rotation
9. A camera as defined in claim 4, wherein each of said data rings
has its entire circumference comprising a data carrier portion and
a gear portion, said data carrier portion being wrapped with a film
having printed indicia thereon, said film being secured to said
data carrier portion by wedging the opposite ends of the film into
recesses provided by said gear portion.
10. A camera provided with a device for photographing the date of
photo-taking comprising:
data rings of transparent material carrying indicia thereon,
said camera having a film chamber and a light-proof frame, said
data rings being disposed between the film chamber and the
light-proof frame,
display rings connected to said data rings for operating them
exteriorly of said camera, and carrying thereon indicia identical
with those on said data rings, said display ring being disposed at
the bottom of said camera and said indicia being observed from the
front of said camera,
a lamp for illuminating said indicia on said data rings,
an optical system for directing the images of said indicia on said
data rings illuminated by said lamp to a part of a focal plane of
an objective lens,
a slit provided between said data rings and said optical system for
directing a selected set of said indicia to said optical
system,
a shutter mechanism, and
a time control device actuated by releasing said shutter for
turning said lamp on for a predetermined length of time, said time
control device being adjustable in accordance with the sensitivity
of a film used in said camera, and having a main switch for
preparing said camera for data photographing,
a data field display member capable of shifting from and into a
field of a finder of said camera, said data field display member
shifting in response to the closing and opening of said main
switch, thereby indicating whether data photographing can be
effected or not.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a camera, and more particularly
to a camera provided with a device for automatically photographing
the data such as dates of photographing.
2. Description of the Prior Art
U.S. Pat. No. 2,813,469 shows a camera comprising a casing, a
window in the casing, an exposure frame in the casing and having a
principal aperture for framing the picture to be taken and an
auxiliary aperture through which an identifying numeral may be
photographed on the film exposed, and a rotary graduated dial
having identifying numerals thereon, with this structure, the dial
is advanced a step each time the film is advanced to bring
successively identifying numerals of the dual successively into
position to register on the film through said auxiliary aperture.
As other prior arts, U.S. Pat. No. 3,185,054 is mentioned.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a camera with
which signals representing the data such as dates of photographing
can be distinctly photographed in a portion of a photographing film
irrespective of various photographing conditions such as film
sensitivity, filter factor, f-value of the objective lens, shutter
time, photographing distance and so forth.
It is a further object of the present invention to provide a camera
of the described type in which a data photographing button is
operable in response to the movement of a shutter button to control
the time for starting to turn on a data illuminator lamp and
accordingly control the time during which the lamp is maintained
turned on.
According to a feature of the present invention, the surface of the
data carrier members and a photographing film are disposed in
conjugate relationship with respect to a data projection lens so
that data signals on the data carrier members illuminated by an
illuminator lamp may be projected on the surface of the
photographing film and that an image light flux passing through an
objective lens and the light flux carrying the data signals may
overlap each other in the field of view defined on the
photographing film by the aforesaid image light flux. In addition,
means having a time constant circuit available for various
photographing information inputs is provided to automatically
control the quantity of light to which the data signals are
exposed, thereby automatically controlling the quantity of light
from the aforesaid illuminator lamp.
The above and othere objects and features of the present invention
will be fully understood from the following detailed description of
various embodiments thereof when taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically shows an example of the control circuit for
controlling the lighting-up time of the lamp used as light source
for illuminating the data carrier members.
FIG. 2 is a partly sectional front elevation of the data
illuminator unit.
FIG. 3 is a schematic representation of a camera incorporating the
data illuminator unit of FIG. 2, and showing the essential part
thereof in horizontal cross section.
FIG. 4 is a vertical cross-sectional view showing a modified form
of the data illuminator unit.
FIG. 5 is a perspective view of a data ring forming a part of the
data illuminator unit shown in FIG. 4.
FIG. 6 is a schematic illustration of an optical system for
directing the data image to the photographing film surface.
FIG. 7 is a bottom plan view of a camera incorporating the data
illuminator unit of FIG. 4.
FIG. 8 is a front view of the same camera.
FIG. 9 schematically shows another example of the electric circuit
in the device for turning on the data illuminator lamp according to
the present invention.
FIG. 10 is a fragmentary plan view, partly in horizontal section,
of the data photographing mechanism incorporating the device of
FIG. 9.
FIG. 11 is a perspective view of a data ring used in FIG. 10.
FIGS. 12 and 13 are horizontal cross-sectional views showing
further modifications of the data photographing mechanism which
employ data rings having reflective surfaces.
FIG. 14 is a perspective view of a prism used in FIGS. 10, 12 and
13 to direct the data image to the photographing film surface.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1, there is shown a specific example of the
circuit arrangement for controlling the lighting-up time of a lamp
for illuminating data carrier members. The circuit is very much
simplified in arrangement and compact in dimensions as well as
improved in performance and economical in manufacturing cost. The
circuit illustrated in FIG. 1 is directed to turn on the
illuminator lamp for a predetermined length of time and includes a
time constant circuit comprising a resistor R1 and a capacitor C, a
first transistor T1 having its base connected with the output of
the time constant circuit through a start S2, a second transistor
T2 having its base connected with the collector of the first
transistor T1, and a lamp L as a load connected with the collector
of the second transistor T2. The circuit is such that power is
supplied from a power source such as battery E to the circuit when
a main switch S1 is closed.
The start switch S2 is such that it is short-circuited for a short
time (say, 10 milli-seconds) in response to the depression of a
shutter button (not shown) so as to charge the capacitor C in
accordance with the small time constant of the time constant
circuit R1-C. A resistor R2 is provided as the output resistor of
the transistor T1.
In operation, if the main switch S1 is first closed, the transistor
T1 and accordingly the transistor T2 will be rendered
non-conductive since the capacitor C is not charged then, and
thereby the lamp L will not turn on. Thus, the power consumption of
the power source may be extremely minimized.
With the switch S1 closed, the unshown shutter button is then
depressed to short-circuit the start switch S2 for a short time in
response thereto. The time during which such short-circuiting
continues is set to a sufficiently smaller value then the time
constant provided by the combined resistance of the input impedance
of transistor T1 and resistor R3 and the capacitor C. Of course,
the time constant of the time constant circuit R1-C is selected to
a sufficiently smaller value than the short-circuiting time of the
start switch S2. Thus, the short-circuiting of the start switch S2
causes the capacitor C to be charged through the resistor R1, and
the charging voltage renders both transistors T1 and T2 conductive
to thereby turn on the lamp L. During the short-circuiting of the
start switch S2, which is opened after a short time, the charge in
the capacitor C has begun to be discharged through the base-emitter
of the transistor T1 in accordance with the time constant provided
by the combined resistance of the input impedance of transistor T1
and resistor R3 and the capacitor C. During that while the
transistors T1 and T2 both remain conductive to maintain the lamp L
turned on for a predetermined length of time, whereafter both
transistors turn off so as to be ready for the next cycle of
operation.
With the circuit arrangement described above, the lighting-up time
of the lamp L may be made substantially constant irrespective of
the possible irregular operation of the start switch resulting from
the manual actuation, by selecting the time constant of the
capacitor C and the aforesaid combined resistance to a greater
value than the short-circuiting time of the start switch S2.
In addition, by employing a variable resistor as resistor R3 so
that it can be controlled in accordance with the film sensitivity
or like factor, the lighting-up time of the lamp as automatic
data-carrier illuminator may be automatically controlled so as to
ensure desired data to be properly projected upon the surface of a
photographing film.
To stabilize the operation of the start switch S2, use may be made
of such means as reed switch, no-contact switch or the like. The
switch may advantageously be a positively operating switch to
prevent chattering or like phenomenon.
In FIG. 2, there is shown a partly sectioned front view of the data
illuminator unit which may be applied to the camera of the present
invention as schematically shown in FIG. 3, where the essential
part thereof is shown in cross section.
Referring to FIGS. 2 and 3, a camera body 1 includes therein a film
chamber 2, a light-proof frame 3, a space 4 defined between the
film chamber 2 and the light-proof frame 3, and a cylindrical
hollow shaft 6 disposed in the space 4 in parallelism to the width
of a film F and having a slit 5 formed in the side wall thereof.
Rotatably mounted around the shaft 6 at one end thereof are data
rings such as year representing ring Y, month representing ring M
and day representing ring D, which are all formed of
light-transmitting material and disposed in end-to-end relationship
for movement relative to each other. The outer side wall surfaces
of these data rings carry various numbers representing years,
months and days, respectively. If desired, the numbers representing
the months may be replaced by alphabetical characters representing
the names of the months. The shaft 6 has the illuminator lamp L
disposed within the hollow cylindrical space therein so that one of
the numbers on each ring Y, M and D which is then confronting the
slit 5 of the shaft 6 may be illuminated by the lamp L from within
the shaft. The particular numbers on the rings Y, M and D thus
illuminated may be optically directed via mirror 8 and lenses
9.sub.1 and 9.sub.2 to a photographing lens L.sub.0 in superposed
relationship with one another, so that these numbers may be
projected upon the photographing film F at a side edge portion
thereof. At the opposite end portion of the shaft 6 there are also
rotatably mounted viewing rings Y', M' and D', which are
interconnected to the respective data rings Y, M and D by reduced
connecting portions as clearly shown in FIG. 2. The viewing rings
Y', M' and D' also carry the same numbers at the same locations as
those on the data rings Y, M and D, so that the numbers on the
respective viewing rings Y', M' and D' which correspond to the
particular numbers on the data rings Y, M and D which are then
confronting the slit 5 may be viewed through a front window 10
formed in the camera body 1. The respective ring pairs Y-Y', M-M',
and D-D' may be rotated for setting independently of one another by
rotating setting gears 14, 15 and 16 which are partly projected
outwardly of the camera body so as to be manually operable
exteriorly of the camera.
In the illustrated embodiment, the rings Y-Y', M-M' and D-D' are of
the end-to-end connected construction, whereas they may
alternatively be of a unitary construction formed of a
light-transmitting material. To enable the rings Y', M' and D' to
be rotated from outside the camera body, gears 11, 12 and 13 may be
provided integrally with these respective viewing rings so as to
engage the projected setting gears 14, 15 and 16 respectively.
A ratchet pawl 17 is provided in opposed relationship with each of
the gears 11, 12 and 13 for engagement therewith, and a window 18
is formed in the light-proof frame 2. A magnifier 19 is disposed
across the window 10.
Turning again to FIG. 1, reference numeral 20 designates an arm
extending from a main switch operating button 21 and adapted to
shift a data field display board 22 from and into the field of view
of a finder in response to the closing and opening of the main
switch S1. The data field display board 20 displays in the field of
view of the finder whether the data photographing can be effected
or not, and if formed of transparent material, the data field
display board 22 can transmit the photographing field of view, and
this will be useful to define a photographing surface. Instead of
such a data field display board, either a data display lamp may be
disposed in the field of view of the finder or use may be made of
such an arrangement that the data signals per se may be directed to
the field of view of the finder through optical fiber or like
means.
The lamp L may advantageously be disposed within the hollow shaft 6
in axially offset relationship with the slit 5 of the shaft as
shown in FIG. 2 so that light from the lamp may effectively reach
the slit 5. When predetermined numbers on the data rings Y, M and D
are illuminated by the lamp L disposed within the hollow shaft 6,
the light from the lamp will pass through the slit 5 with a
substantially uniform distribution of intensity, which will in turn
result in a substantially uniform intensity of data signals
representing predetermined numbers on the data rings Y, M and D
illuminated by the lamp L through the slit 5, and such data signals
of uniform intensity will be projected as a secondary light source
upon the surface of the photographing film. The inner wall surface
of the hollow shaft 6 serves as a reflective surface 23, which,
together with the axially offset relationship between the lamp L
and the slit 5, is useful to eliminate and adverse effect which may
result from the particular configuration of the lamp filament,
thereby achieving the described uniform distribution of light
intensity with a high efficiency.
In the embodiment now under discussion, the year, month and day
representing rings Y, M and D are formed of diffusive plastic ring
members Y1, M1 and D1 and sensitized photographic film layers
Y.sub.0, M.sub.0 and D.sub.0 bonded around the respective ring
members, the film layers having thereon positively printed numbers
representing years, months and days. As shown, the film layers
Y.sub.0, M.sub.0 and D.sub.0 on the rings Y, M and D are disposed
in partly overlapping relationship with one another so as to
prevent leakage of the light from the lamp through the gaps between
adjoining rings. It is of course desirable that the inner wall
surfaces of the light-proof frame 3 be pre-treated for
non-reflection so as to eliminate any undesirable phenomenon such
as secondary reflection of the photographing light.
Thus, the present invention enables the film sensitivity to be
corrected by correcting the lighting-up time of the illuminator
lamp L with its light maintained at a substantially uniform color
and temperature, and this is highly effective and practical for
industrial purposes.
FIGS. 4 to 8 show a modification of the above-described data
illuminator unit. In this alternative form of the present
invention, a base plate 31 is provided in a space between the
light-proof frame and the film chamber disposed in the camera body,
the base plate being parallel to the width of the photographing
film (not shown). Two cylindrical shafts 32 and 33 are securely
mounted on the base plate 31 in such a manner that their respective
axes are parallel to the length of the photographing film.
The shaft 32 has an axially extending slit 34 formed through the
side wall thereof. Around the shaft 32 are rotatably fitted
transparent data rings 35, 36 and 37 representing days, months and
years and having their outer wall surfaces flush with one another.
The day ring 35 and year ring 37 comprise data portions 35.sub.1
and 37.sub.1 and gear portions 35.sub.2 and 37.sub.2, respectively,
and these data and gear portions are disposed to form individual
complete circumferences, respectively. Unlike these two rings, the
month ring 36 comprises a data portion 36.sub.1 and a gear portion
each forming a half of a complete circle, as particularly shown in
FIG. 5. Such formation of the three data rings 35 to 37 leads to
the advantage such as a reduced total width of the data ring
assembly and accordingly to the compactness of the camera.
Data 38 may be impressed on the side wall of each data ring, but it
is also possible to attach a corresponding length of data film 39
to the side wall of the ring by wedging the opposite ends the film
at 40 as shown in FIG. 5 so that the data 38 may be replaced with
ease.
The shaft 33 has gears 41, 42 and 43 rotatably mounted thereon and
engaging the gear portions 35.sub.2, 36.sub.2 and 37.sub.2 of the
data rings 35, 36 and 37, respectively. As shown, the gears 41 to
43 are partly projected outwardly of the camera body so that they
may be operated from the exterior of the camera. Data display rings
44, 45 and 46 are detachably secured to the gears 41, 42 and 43
respectively, and these rings carry thereon the same data as those
on the data rings 35 to 37. The data on the display rings 44-46 are
located so that they may be viewed from the exterior of the camera
through a display window 47 (FIG. 8). The detachable connection
between the gears 41-43 and the display rings 44-46 as shown in
FIG. 4 facilitates the assemblage of the entire data illuminator
unit with the data both on the respective data rings 35-37 and
display rings 44-46 kept in coincidence with each other.
The data to be photographed may be readily changed simply by
rotating the gears 41-43 while viewing the data appearing at the
display window 47 provided in the front wall of the camera, as
shown in FIG. 8. The window 47 may alternatively be formed in the
rear wall of the camera.
As shown in FIG. 4, an illuminator lamp L is disposed within the
hollow shaft 32, and there is further provided an optical system
49-52 comprising a combination of prism, mirror and lenses for
directing the data illuminated by the lamp L to the photographing
film. The optical system may be made compact by disposing a mirror
52 between two lenses 50 and 51 in the manner as shown in FIG. 6. A
mask 53 may be provided closely adjacent to the data rings 35-37 so
as to prevent any lamp light from leaking through the gaps between
adjoining data rings.
Thus, when the lamp L is turned on in response to a shutter
release, those of the data on the respective data rings 35, 36 and
37 which are then confronting the slit 34 of the shaft 32 may be
illuminated by the lamp and the images thereof are directed through
the optical system 49-52 so as to be formed on a side edge of the
photographing film.
In the embodiment described just above, the data rings and
associated display rings are disposed in the space between the
light-proof frame and the film chamber within the camera body in
such a manner that the axes of these rings are parallel to the
length of the photographing film, and the data rings surround the
illuminator lamp while the display rings are disposed so as to be
operable exteriorly of the camera. This arrangement permits the
width of the data ring assembly to be considerably smaller than the
outer diameter thereof, as compared with the previous embodiment
wherein the data rings are disposed with their axes parallel to the
width of the photographing film, and this in turn leads to a
reduced thickness of the camera body and accordingly to the
compactness of the entire camera.
FIGS. 9 to 11 show a further embodiment of the present invention in
which transparent data rings and operating rings for operating
these data rings exteriorly of the camera are all rotatably mounted
around the body tube of the camera.
In FIG. 10, there are seen a camera body 61, a pressurized plate
62, a film chamber 63, a light-proof frame 64, a body tube 65 for
supporting a lens L.sub.0, and transparent data rings 67.sub.1
-67.sub.3 rotatably mounted around the body tube 65. It should be
noted that data A to be photographed are provided on the inner wall
surface of the data rings as shown in FIG. 11. Operating rings
68.sub.1 -68.sub.3 for operating the respective data rings 67.sub.1
-67.sub.3 exteriorly of the camera carry display data A' on the
outer wall surface thereof, the display data A' corresponding to
the data A on the data rings 67.sub.1 -67.sub.3 respectively. As
seen in FIG. 11, each data ring 67 and each operating ring 68 may
be provided by forming a transparent ring member 69 into two
concentric inner and outer rings integrally connected together at a
connecting portion 69.sub.1 with a discontinuous annular groove 70
defined therebetween, so that the inner and outer rings may provide
the data ring 67 and the operating ring 68 respectively.
Alternatively, the data and operating rings 67 and 68 may be formed
of separate members, and in this case the operating members 68 need
not be of transparent material. An illuminator lamp L is disposed
in the groove 70 and secured to the camera body, and as shown in
FIG. 9, the lamp L may be turned on for a predetermined length of
time in response to a shutter release. An optical system for
forming the images of data on the surface of a photographing film
(not shown) is provided by a prism 72 (FIG. 14) and a photographing
lens 73. In the light path of the optical system there is provided
a light-leakage preventive member 74 adapted to open and close in
response to a shutter release. Coaxially and coextensively with the
data rings, there is mounted a fixed ring 75 having a reference
mark 76 provided on the outer wall surface thereof (FIG. 10).
In operation, the illuminator lamp circuit is closed in response to
a shutter release to thereby turn on the lamp L while opening the
light-leakage preventive member 74. Thus, those of the data on the
data rings which are then confronting the slit 77 are illuminated
by the lamp L and their images are formed through the optical
system 72-73 on the photographing film at one side edge thereof. If
the data to be photographed are to be changed, the operating rings
68 may be manually rotated so as to register any desired data
thereon with the reference mark 76 on the fixed ring 75.
FIG, 12 illustrates a modification of the FIG. 10 data illuminator
unit, in which the illuminator lamp L is disposed in the space
between the film chamber 63 and the light-proof frame 64 so that
data on the data rings 67 may be illuminated through a reflective
surface provided over the outer surfaces of the data rings.
FIG. 13 shows a further mofification of the data illuminator unit
in which discrete reflective surfaces 78 are formed on the
respective data rings 67.sub.1, 67.sub.2 and 67.sub.3 representing
days, months and years, so that the data on the respective data
rings 67.sub.1 -67.sub.3 may be uniformly illuminated.
The illuminator lamp circuit will now be described with reference
to FIG. 9. A capacitor C and a resistor R3 are provided as time
constant elements, R3 being a variable resistor whose resistance
value is variable in accordance with the selected film sensitivity.
Also provided are a main switch S1 and a normally open switch S2
which is adapted to close just prior to the shutter release in
response to the depression of a shutter button 71. A switch S3 is
adapted to open in response to the shutter release but it is
normally closed during film winding operation. The shutter button
71 has a pin 71' adapted to engage a release lever 8 outwardly
extending from a shutter driving ring 80 to thereby release the
shutter. The shutter driving ring 80 has a shutter charge lever 82
outwardly extending therefrom and is rotatable so that the charge
lever 82 comes through a final charge position as indicated by
imaginary lines 82' to a maximum charge position as indicated by
imaginary lines 82". The shutter charge lever 82 can return from
the position 82" to the position 82' in response to the movement of
an unshown film winding lever. The shutter button 71 is provided
with an adjust screw for adjusting the closing position of the
switch S2. Transistors T1 and T2 and power source E are provided in
the manner as shown.
In operation, when the shutter is charged, the driving ring 80 is
rotated in the direction indicated by arrow a until the charge
lever 82 comes to the position 82", whereafter the ring 80 is
rotated back to stop the charge lever at the position 82'. At this
time the switch S3 is closed. When the shutter button 71 is
depressed to effect photographing, the switch S2 is closed just
before the shutter is released, thereby allowing the capacitor C to
be charged through the resistor R1. When the shutter is then
closed, the switch S3 is opened by the charge lever 82 which has
been moved from the position 82' to the solid-line position,
thereby stopping the charge to the capacitor C. The switch S1 is
preadjusted by means of the adjust screw 13 so that the described
switching cycle may range from approximately 10 to 20
milli-seconds.
Upon stoppage of the charge to the capacitor C, the capacitor
discharges through the base-emitter of the transistor T1, and until
the transistor T1 is rendered non-conductive after a length of time
determined by the time constant of the time constant circuit C-R,
the transistor T2 remains conductive to turn on the lamp L. If it
is desired to vary the lighting-up time of the lamp L in accordance
with the film sensitivity, the variable resistor 3 may be adjusted
to vary the time constant of C-R.
* * * * *